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Sequelize Model Validation

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Set Validations for a Model

3:09 with Guil Hernandez

Let's begin setting up validations and constraints for the User model to prevent invalid data from being entered into the database.

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    Let's begin setting up validations and constraints for 0:00
    the user model to prevent invalid data from being entered into the database. 0:03
    As I demonstrated in the previous video, 0:08
    null by default is an allowed value for any attribute or column of a model. 0:11
    Sending an empty post request or even setting a property explicitly to 0:16
    null allows User.create() to be called here in the post users route and 0:21
    successfully create a new user entry. 0:26
    We don't want that. 0:28
    First, we'll make sure that a null value is not allowed for name, 0:30
    email, birthday, and password using the Sequelize allow null check. 0:34
    If any of these attributes are null, 0:39
    the new user entry will not be stored and a validation error will be thrown. 0:42
    Inside the name attributes object, 0:47
    I'll add the allowNull option and set it to false. 0:51
    I'll do the same for email, then birthday, and finally password. 0:56
    Over in Postman, I'll try to send a post request to the API 1:11
    users routes with missing attributes or 1:16
    fields in the body, an empty object for example. 1:19
    Notice how I receive a 400 bad request HTTP status code back from the server. 1:23
    And the response body displays the validation error messages thrown by 1:29
    sequelize, preventing unreliable data from being stored in the database. 1:33
    So here in the post users route handler function in routes.js, 1:37
    the error is thrown in the try block, user.create does not get called. 1:42
    So the statements in the catch block execute instead. 1:48
    I've also added a console.log statement here in the catch block, 1:52
    where I'm logging error.name. 1:56
    So we're able to see the error being thrown. 1:58
    Notice in the terminal that the error log is a sequelize validation error. 2:01
    As you've noticed from working with sequelize in previous lessons, 2:08
    the format of its errors contains more information than what's typically 2:12
    necessary to return to the client. 2:16
    So for this workshop, 2:18
    I have also transformed errors to a more straightforward format by first 2:19
    checking if the error caught by catch is a sequelize validation error or 2:25
    a sequelize unique constraint error, which I'll talk more about later. 2:30
    Then I'm iterating over the errors array that's in the sequelize error 2:35
    passed to the catch block to access only the error messages and 2:41
    sending the error messages back to the client, 2:46
    as you can see here in the response body. 2:50
    Else any other error will be thrown here and caught up here and 2:54
    the asyncHandler function that wraps each route. 3:00
    More about this handler in the teachers notes. 3:05

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